poi sync:
  51785 - Allow XSSF setForceFormulaRecalculation to work with the minimal ooxml-schemas jar(poi-developers)
  New PackagePart method getRelatedPart(PackageRelationship) to simplify navigation of relations between OPC Parts(poi-developers)
sync: avoid exceptions when using POI in Tika, see BUgs 51771 and 51770
OpenXml4Net has been completed. The following issues has been fixed.

52540 - Relax the M4.1 constraint on reading OOXML files, as some Office produced ones do have 2 Core Properties, despite the specification explicitly forbidding this(poi-developers)
(antony)51949 - Avoid NPE on double close of ZipFileZipEntrySource(poi-developers)
52665 - When reading from a ZipFileZipEntrySource that has already been closed, give IllegalArgumentException rather than NPE(poi-developers)
Add File based constructor to OPCPackage, alongside existing String one (which constructed a File from the string internally)(poi-developers)
52211 - avoid unnessary re-coverting content types to US-ASCII, it can cause exceptions on ibm mainframes(poi-developers)
53282 - Avoid exception when parsing OPC relationships with non-breaking spaces(poi-developers)